Gender identity conversion efforts during early childhood quadruple lifetime risk of suicidal behavior for transgender people, a study of almost 28,000 adults has determined.

The findings prompted the authors to issue a blanket warning against the controversial treatment, which already has been decried by several medical associations.

“Our results support policy positions … which state that gender identity–conversion therapy should not be conducted for transgender patients at any age, Jack L. Turban, MD, and colleagues wrote in JAMA Psychiatry.

The American Academy of Child and Adolescent Psychiatry, the American Psychiatric Association, the American Academy of Pediatrics, and the American Medical Association all strongly warn against any kind of gender conversion efforts.

The significantly increased risk of suicidal behavior was similar whether the gender identity–conversion effort (GICE) was administered by a clinician or a cleric. “This suggests that any process of intervening to alter gender identity is associated with poorer mental health regardless of whether the intervention occurred within a secular or religious framework,” wrote Dr. Turban of Massachusetts General Hospital, Boston, and coauthors.

The study – the largest of its kind thus far – comprised 27,715 transgender adults included in the 2015 U.S. Transgender Survey, conducted by the National Center for Transgender Equality.

In the current study, investigators focused on the question: “Did any professional (such as a psychologist, counselor, or religious advisor) try to make you identify only with your sex assigned at birth (in other words, try to stop you being trans)?”

They compared responses among subjects who reported exposure to GICE before age 10 years with those who did not.

Subjects were aged a mean of 31 years when they participated in the survey. Slightly less than half (42.8%) were assigned male sex at birth. Most (19,751) had discussed their gender identity with a professional. Nearly 20% (3,869) reported some exposure to GICE; 35% said a religious adviser had conducted the effort.

In this group, exposure had significant negative lifetime effects on mental health. These subjects were at a 56% increased risk of psychological distress within the month before taking the survey (odds ratio, 1.56), and more than twice as likely to have tried at least once to end their lives by suicide (OR, 2.27).

But the negative effects were even more pronounced among the small group of 206 who reported exposure to GICE before they were 10 years old. In a multivariate analysis adjusted for demographics, GICE before age 10 more than quadrupled the risk of lifetime suicide attempts (OR, 4.15). Again, it didn’t matter whether a medical or religious professional administered GICE.

“A plausible association of these practices with poor mental health outcomes can be conceptualized through the minority stress framework; that is, elevated stigma-related stress from exposure to GICE may increase general emotion dysregulation, interpersonal dysfunction, and maladaptive cognitions,” the investigators wrote. “Although this study suggests that exposure to GICE is associated with increased odds of suicide attempts, GICE are not the only way in which minority group stress manifests, and thus, other factors are also likely to be associated with suicidality among gender-diverse people.”

The rate at which transgender people are exposed to GICE appears to be higher than that experienced by cisgender nonheterosexual people, the authors noted. “One potential explanation for this is that, compared with persons in the sexual-minority group, many persons in the gender-minority group must interact with clinical professionals to be medically and surgically affirmed in their identities. This higher prevalence of interactions with clinical professionals among people in the gender minority group may lead to greater risk of experiencing conversion effort.”

The authors cited the sample size of the study as one of its many strengths. One limitation includes the study’s cross-sectional design.

Dr. Turban reported collecting royalties from Springer for an upcoming textbook about pediatric gender identity. The other coauthors reported no disclosures.